Quantum computers which perform computations using a quantum-mechanical superposition state have been actively studied. As one of methods/configurations for quantum computations, a frequency domain quantum computation is known in which quantum bits (qubits) used for computations are distinguished from one another in a frequency domain. In frequency domain quantum computations, the qubits are distinguished regardless of their positions, and thus, a gate error may occur due to application of operation light with detuning to qubits that are not intended to be manipulated. There has been a demand to suppress the gate error resulting from such a crosstalk, while allowing efficient performance of a quantum gate based on frequency domain quantum computations.